1. Field
The present disclosure relates generally to processing data and in particular to processing data from responses of a structure to an input wave form. Still more particularly, the present disclosure relates to a method, apparatus, and computer usable program code for identifying anomalies in a structure.
2. Background
Composite and metallic aircraft structures may be susceptible to internal changes that may occur from fatigue, impacts, and other events or conditions. Composite materials typically have a minimal visual indication of these types of changes. As a result, an aircraft may be inspected to assess the integrity of the structure on a periodic basis, or after visual indications of surface anomalies, such as dent and scratch.
For example, impacts to a structure, such as an aircraft, may occur during cargo loading and unloading. Inspections of the structure of an aircraft may be time consuming and costly in terms of the time and skill needed to perform the inspection. Further, an airline may incur lost revenues from the aircraft being out of service.
Health monitoring techniques have been developed and used to monitor structures and their components. These techniques often build the health monitoring systems into the structures. These health monitoring systems may be used to determine whether changes have occurred to these structures over time.
Sudden changes in environments, such as electromagnetic effects, mechanical stresses, and other environmental effects may affect the integrity of various materials and structures over time. By having health monitoring systems built into or associated with the structures to monitor the structures during use, appropriate measures and responses may be taken to prevent catastrophic failures and may prolong the life span of these structures.
The monitoring of structures may include various non-destructive evaluation methods, such as ultrasonic testing or x-ray testing. Ultrasonic testing uses contact-based transducers to mechanically scan a structure. These distributed sensors and actuators may be surface mounted on the structure or may be embedded in the structure to generate and propagate control of diagnostic signals into the structure being monitored.
A structural health monitoring system is based on using a transmitter and a sensor configuration to transmit waveforms at various frequency ranges and acquire data from the responses. Often times, transducers may function both as a transmitter and a sensor. Although structural health monitoring systems may provide an automated on board system for detecting and characterizing anomalies or changes that may require maintenance, these types of systems may provide for false indications that further inspection and/or maintenance may be needed.
These health monitoring systems may have inaccuracies caused by environmental conditions and/or components within the health monitoring system. For example, changes in temperature may affect the results generated by the health monitoring system.
Therefore, it would be advantageous to have a method and apparatus that overcomes the problems described above.